Element chip manufacturing method

ABSTRACT

An element chip manufacturing method includes a preparation process of preparing a substrate which includes a first surface provided with a bump and a second surface and includes a plurality of element regions defined by dividing regions, a bump embedding process of adhering a protection tape having an adhesive layer to the first surface and embedding. The element chip manufacturing method includes a thinning process of grinding the second surface in a state where the protection tape is adhered to the first surface and thinning the substrate, after the bump embedding process, a mask forming process of forming a mask in the second surface and exposes the dividing regions, after the thinning process, a holding process of arranging the first surface to oppose a holding tape supported on a frame and holding the substrate on the holding tape.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure is related to a method for manufacturing anelement chip by singulating a substrate which includes a bump.

2. Description of the Related Art

As a method for singulating a substrate including a plurality of elementregions defined by dividing regions, a method (plasma dicing) for plasmaetching the dividing regions to a depth which extends from one surfaceof the substrate to the other surface is known. The substrate, ingeneral, includes a semiconductor layer, a circuit layer laminated onthe semiconductor layer, and a projection (bump) disposed on the circuitlayer and containing a metallic element such as an electrode pad(bonding pad) and a solder ball. An element chip including the circuitlayer and the bump is formed by plasma etching the dividing regions ofthe substrate.

The plasma dicing is performed by placing the substrate on a stageinstalled in a plasma processing apparatus. Generally, the substrate issingulated in such a way that the semiconductor layer is placed on thestage to be opposed to the stage and plasma is irradiated from a surfaceside (circuit layer) on which the bump of the substrate is disposed (seePTL 1). This is because damage due to contact between the bump and thestage is prevented and a pickup of an element chip to be performed aftersingulation becomes easy. In PTL 1, the substrate is plasma-diced in astate where the electrode pad is exposed to a surface of the circuitlayer.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Unexamined Publication No. 2002-93749

SUMMARY OF THE INVENTION

In a case where as described above, the substrate is plasma diced fromthe surface of the circuit layer including an exposed bump, the bump isexposed to plasma. For that reason, a metal constituting the bump isscattered. When the scattered metal is deposited to the inside of theplasma processing apparatus, generation of plasma may become unstable orthe substrate which is a plasma dicing target may be contaminated withmetal. When the scattered metal is deposited to the substrate again, thescattered metal becomes a fine mask (micromask) and desired etching isnot conducted. The scattered metal is deposited to the substrate againor a portion of the bump is etched such that reduction in electricaldevice characteristics and reliability of an element chip to be obtainedmay be caused.

In order to suppress the bump from being irradiated with plasma, amethod in which a resist mask covering the bump and including an openingin the dividing region is formed may be considered. In this case, theresist mask needs to have a sufficient thickness such that the bump isnot exposed during plasma dicing. The resist mask is generally formed byperforming rotary coating (spin coating) on the substrate with resistsolution. In a case where the substrate having a flat surface and athickness of T is plasma-diced, a needed film thickness M of the resistmask is at least T/R or more when R is used as a mask etch selectivityunder the etching condition thereof. Generally, the mask film thicknessM is set to T/R×1.1 to T/R×2.0 by taking process variations intoaccount. Resist solution used in spin coating has flowability and thus,in a case where the bump is present in the surface of the substrate, aresist film thickness M of a head top part of the bump becomes thinner.For that reason, the resist film thickness needs to be greater than thatdescribed above such that the head top part of the bump is not exposedduring the plasma dicing. Accordingly, a use amount of the resistsolution is significantly increased, the time required for formation ofthe resist mask is increased, and production cost is increased.

The resist mask is removed by plasma ashing after the plasma dicing.When the resist mask is thick, the time required for plasma ashingbecomes longer and thus, productivity is reduced. The head top part ofthe bump is exposed to plasma for a long time during plasma ashing andthus, the surface of the bump is easily oxidized. Accordingly,deterioration of device characteristics, for example, increase incontact resistance of the substrate is easily generated. As such, in acase where the bump is covered with the resist mask in order to suppressthe bump from being irradiated with plasma, there is a problem fromproductivity and device characteristics point of view.

One aspect of the present disclosure is related to an element chipmanufacturing method including a preparation process, a bump embeddingprocess, a thinning process, a mask forming process, a holding process,a placement process, and a singulation process. The preparation processis a process of preparing a substrate which includes a first surfaceincluding an exposed bump and a second surface opposite to the firstsurface and includes a plurality of element regions defined by dividingregions. The bump embedding process is an embedding process of adheringa protection tape having an adhesive layer to the first surface andembedding at least a head top part of the bump into the adhesive layer.The thinning process is a process of grinding the second surface in astate where the protection tape is adhered to the first surface andthinning the substrate, after the bump embedding process. The maskforming process is a process of forming a mask which covers elementregions in the second surface and exposes the dividing regions, afterthe thinning process. The holding process is a process of arranging thefirst surface to oppose a holding tape supported on a frame and holdingthe substrate on the holding tape. The placement process is a process ofplacing the substrate on a stage provided inside of a plasma processingapparatus through the holding tape, after the mask forming process andthe holding process. The singulation process is a process of plasmaetching the dividing regions to a depth which extends from the secondsurface to the first surface and forming a plurality of element chipsfrom the substrate, after the placement process.

According to the present disclosure, it is possible to singulate asubstrate without reducing productivity while suppressing degradation ordamage of a bump by plasma.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a conceptual diagram illustrating an element chipmanufacturing method according to a first exemplary embodiment of thepresent disclosure using a cross section of a substrate;

FIG. 1B is a cross-sectional view illustrating another example of thesubstrate used in the first exemplary embodiment;

FIG. 1C is a conceptual diagram illustrating another example of a bumpexposing process conducted in the first exemplary embodiment using thecross section of the substrate;

FIG. 2 is a cross-sectional view schematically illustrating aconfiguration of a substrate according to an exemplary embodiment of thepresent disclosure;

FIG. 3A is a cross-sectional view schematically illustrating a laminatedstructure formed with the substrate and a protection tape in theembedding process of the first exemplary embodiment;

FIG. 3B is a cross-sectional view schematically illustrating anotherlaminated structure formed with the substrate and the protection tape inthe embedding process of the first exemplary embodiment;

FIG. 4A is a top view schematically illustrating a transport carrieraccording to the exemplary embodiment of the present disclosure;

FIG. 4B is a cross-sectional view taken along line IVB-IVB of FIG. 4A;

FIG. 5 is a conceptual diagram illustrating a schematic structure of aplasma processing apparatus according to an exemplary embodiment of thepresent disclosure using a cross-section; and

FIG. 6 is a conceptual diagram illustrating an element chipmanufacturing method according to a second exemplary embodiment of thepresent disclosure using a cross-section of a substrate.

DETAILED DESCRIPTION OF EMBODIMENTS

In the present exemplary embodiment, an element chip is manufactured bya method including a preparation process, a bump embedding process, athinning process, a mask forming process, a holding process, a placementprocess, and a singulation process. The preparation process is a processof preparing a substrate which includes a first surface including anexposed bump and a second surface opposite to the first surface andincludes a plurality of element regions defined by dividing regions. Thebump embedding process is an embedding process of adhering a protectiontape having an adhesive layer to the first surface and embedding atleast a head top part of the bump into the adhesive layer. The thinningprocess is a process of grinding the second surface in a state where theprotection tape is adhered to the first surface and thinning thesubstrate, after the bump embedding process. The mask forming process isa process of forming a mask which covers an element region in the secondsurface and exposes the dividing regions, after the thinning process.The holding process is a process of arranging the first surface tooppose a holding tape supported on a frame and holding the substrate onthe holding tape. The placement process is a process of placing thesubstrate on a stage provided inside of a plasma processing apparatusthrough the holding tape, after the mask forming process and the holdingprocess. The singulation process is a process of plasma etching thedividing regions to a depth which extends from the second surface to thefirst surface and forming a plurality of element chips from thesubstrate, after the placement process.

The substrate is plasma-diced from a surface (second surface) oppositeto a first surface which includes the bump. For that reason, the bump ishardly exposed to plasma. With this, the following effects are achieved.

First Effect Stabilization of Plasma Generation

When the bump is exposed to plasma, a metal constituting the bump may bescattered. In a case where the plasma processing apparatus includes aninductive coupled plasma source and has a dielectric member whichtransmits a magnetic field for plasma generation, when the metal (gold,silver, nickel or the like) with inferior reactivity constituting thebump is deposited to the dielectric member, transmission of the magneticfield for plasma generation is blocked. With this, generation of plasmabecomes unstable and reproducibility and stability of etching isreduced. However, according to the present exemplary embodiment, even ina case where the plasma processing apparatus includes the dielectricmember, the metal is suppressed from being deposited to the dielectricmember and thus, generation of plasma is stable and reproducibility andstability of etching is enhanced.

Second Effect Making a Favorable Shape for an Element Chip

When the metal constituting the bump is deposited to the substrateagain, a negative influence is exerted on the shape of the element chip,for example, the metal becomes a micromask during the plasma dicing anda side surface of the element chip is roughened or the like. Thenegative influence on the shape of the element chip may cause reductionin flexural strength of the element chip or molding failure whenpackaging the element chip. However, according to the present exemplaryembodiment, the micromask is hardly formed by the metal during theplasma dicing and thus, an element chip excellent in smoothness of theside surface is obtained. Accordingly, an element chip to be obtained isexcellent in flexural strength and the molding failure is hard to occurwhen packaging elements in the element chip.

Third Effect Suppression of Etching Residue and Etching Stop

When the metal constituting the bump is scattered and deposited to thedividing region of the substrate again, etching residue is generated onthe dividing region. Such an etching residue becomes the cause ofparticles generation and induces defective recognition and pickupfailure in a pickup process after the plasma dicing. For that reason,yield in production is reduced. When an amount of etching residuegenerated in the dividing region is large, etching stop is generated inthe dividing region and deterioration that the substrate cannot besingulated is generated. However, according to the present exemplaryembodiment, the metal is hardly re-deposited to the substrate during theplasma dicing and thus, etching residue is suppressed from beinggenerated in the dividing region. Accordingly, an amount of particles isreduced and recognition performance and pickup performance is increased,and yield in production is enhanced in a pickup process after the plasmadicing. The etching stop is hardly generated in the dividing regionduring the plasma dicing and the yield is enhanced.

Fourth Effect Suppression of Metal Contamination of the Element Chip

When the metal constituting the bump is scattered and is re-deposited toa portion (for example, a surface of a resin protective layer on asurface of the circuit layer and a side surface of the semiconductorlayer) other than the bump of the element chip, metal contamination ofthe element chip occurs. When the element chip is contaminated by metal,device characteristics are reduced. However, according to the presentexemplary embodiment, the metal is suppressed from being re-deposited tothe portion other than the bump of the element chip and thus, metalcontamination of the element chip is hard to occur and devicecharacteristics of the element chip is enhanced.

Fifth Effect Prevention of Bump-etching

When a portion of the bump is etched, electrical characteristics of theelement chip may be changed. However, according to the present exemplaryembodiment, the bump is prevented from being etched and thus, theelectrical characteristics of the element chip is hardly changed.

Sixth Effect Prevention of Bump Degradation

When the bump is exposed to plasma, the bump may change in quality(degradation) such that deterioration occurs. For example, in a casewhere the bump contains copper, when plasma processing using gascontaining sulfur hexafluoride (SF₆) is performed, copper is sulfurizedwith plasma irradiation and reliability is reduced. In a case whereprocess gas or ashing gas contains fluorine or oxygen, an increase incontact resistance or a decrease in connection strength occurs byfluorination or oxidation of the surface of the bump, and reliability isreduced. In a case where process gas contains fluorocarbon such as C₄F₈,a reaction product which contains carbon is deposited to the surface ofthe bump, an increase in contact resistance or a decrease in connectionstrength occurs, and reliability is reduced. However, according to thepresent exemplary embodiment, the bump is hardly degraded during plasmadicing. Accordingly, even in a case where any kind of gas is used,reliability is hardly imp aired.

Seventh Effect Prevention of Bump Damage

According to the present exemplary embodiment, the first surfaceincluding the bump of the substrate is placed on a stage through aholding tape during plasma dicing. For that reason, damage of the bumpcaused by contact of the bump with the stage is suppressed. Thesubstrate is plasma diced from the second surface and thus, the maskwhich covers the element region is formed on the second surface. Forthat reason, the bump exposed to the first surface is hardly influencedby a developer or the like used in formation of the mask. Accordingly,damage of the bump is suppressed also in the mask forming process.

Eighth Effect Omission of Thick Resist Mask

In a case where a thick resist mask is formed on the substrate asdescribed above in order to protect the bump, plasma ashing for a longtime is needed for removal of the resist mask after plasma dicing. Forthat reason, the processing time is increased or deterioration of thedevice characteristics, for example, the head top part of the bump isoxidized by being exposed to plasma in plasma ashing, and contactresistance is increased when electrical connection is performed becomeeasy to occur. However, in the present exemplary embodiment, plasmadicing is performed from a surface opposite to the circuit layer andthus, the thick resist mask described above is not needed and anincrease in manufacturing cost can be suppressed. Also, ashing for along time for removal of the resist mask is omitted and thus, theincrease of the processing time or deterioration of the devicecharacteristics described above is hard to occur.

In the following, with reference to the accompanying drawings,description will be made on a first exemplary embodiment in which thethinning process, the mask forming process, the holding process, and thesingulation process are performed in a state where a protection tape isadhered to the first surface and a second exemplary embodiment in whichthe mask forming process is performed in a state where the protectiontape is adhered to the first surface and the protection tape is peeledoff from the first surface before the holding process.

First Exemplary Embodiment

In the present exemplary embodiment, a thinning process, a mask formingprocess, a holding process, and a singulation process are performed in astate where a protection tape is adhered to a first surface. Amanufacturing method according to the present exemplary embodiment willbe described with reference to FIG. 1A to FIG. 5. (a) to (h) of FIG. 1Aare conceptual diagrams illustrating a manufacturing method according tothe present exemplary embodiment using a cross section of a substrate.FIG. 1B is a cross-sectional view illustrating another example of thesubstrate used in the present exemplary embodiment. FIG. 1C is aconceptual diagram illustrating another example of a bump exposingprocess conducted in the present exemplary embodiment using a crosssection of the substrate. FIG. 2 is a cross-sectional view schematicallyillustrating a configuration of the substrate (before thinning process)according to the present exemplary embodiment. FIG. 3A is across-sectional view schematically illustrating a laminated structureformed with the substrate and the protection tape in an embeddingprocess of the present exemplary embodiment. FIG. 3B is across-sectional view schematically illustrating another laminatedstructure formed with the substrate and the protection tape in theembedding process of the present exemplary embodiment. FIG. 4A is a topview schematically illustrating a transport carrier according to thepresent exemplary embodiment. FIG. 4B is a cross-sectional view takenalong line IVB-IVB of FIG. 4A. FIG. 5 is a conceptual diagramillustrating a schematic structure of a plasma processing apparatusaccording to the present exemplary embodiment using a cross-section. Inthe illustrated examples, for convenience's sake, same referencenumerals are given to members having the same function.

(1) Preparation Process

First, substrate 10 which becomes a singulation target is prepared ((a)of FIG. 1A). Substrate 10 includes first surface 10X and second surface10Y, and also semiconductor layer 11, circuit layer 12 laminated on afirst surface 10X side of semiconductor layer 11, and a plurality ofbumps 13 disposed on circuit layer 12. Substrate 10 is partitioned intodividing regions R1 and a plurality of element regions R2 defined bydividing regions R1. Dividing regions R1 of substrate 10 are etched tothereby obtain element chips 100 each of which includes semiconductorlayer 11, circuit layer 12, and bump 13.

In prepared substrate 10, semiconductor layer 11 may be exposed individing regions R1 as illustrated in FIG. 1B. That is, circuit layer 12may be separated into a plurality of portions according to elementregions R2. Separation of circuit layer 12 may be performed in a processthat forms circuit layer 12 and may be performed with laser scribing,mechanical dicing, or the like before the preparation process aftercircuit layer 12 is formed. As such, in a case where circuit layer 12 ofprepared substrate 10 is separated, etching of circuit layer 12 is notneeded in the singulation process and thus, productivity is enhanced.Substrate 10 is apt to warp by internal stresses possessed by circuitlayer 12 in the thinning process. When substrate 10 is warped, coolingof substrate 10 becomes insufficient during plasma dicing and it isdifficult to conduct a desired plasma dicing. In a case where thethinning process is performed on substrate 10 including circuit layer 12separated in advance, internal stress that becomes the cause of warpingis relaxed. Accordingly, it becomes easy to suppress warping ofsubstrate 10.

The size of substrate 10 is not particularly limited and the maximumdiameter of substrate 10 is, for example, approximately 50 to 300 mm.Also the shape of substrate 10 is not particularly limited and is, forexample, a circular shape and a square shape. An orientation flat or anotched part such as a notch (both are not illustrated) may be providedin substrate 10.

Semiconductor Layer

Semiconductor layer 11 contains, for example, silicon (Si), galliumarsenide (GaAs), gallium nitride (GaN), and silicon carbide (SiC). Thethickness of semiconductor layer 11 after the thinning process whichwill be described later is not particularly limited, is, for example, 20to 1000 μm, or and may be 100 to 300 μm.

Circuit Layer

Circuit layer 12 includes, for example, an insulation film, a metallayer, a resin protective layer (for example, polyimide), and a resistlayer and constitutes a semiconductor circuit, an electronic componentelement, a MEMS, or the like. The thickness of circuit layer 12 is notparticularly limited and is, for example, 10 to 100 μm.

Bump

Bump 13 is a projection containing a metal, for example, an electrodepad and a solder ball. Metals contained in bump 13 are not particularlylimited and includes, for example, copper, an alloy of copper, tin, andsilver, an alloy of silver and tin, an alloy of tin and lead, gold,aluminum, and an aluminum alloy. As will be described later, bump 13 isnot directly exposed to plasma and thus, various metals can be usedaccording to purposes without having to worry about degradation of ametal or a chemical change. The shape of bump 13 is not alsoparticularly limited and may be a square pillar, a cylindrical pillar, amound shape, a ball shape and the like. Height Hb (see FIG. 2) of bump13 may be suitably set according to purposes and is, for example, 20 to200 μm. Height Hb of bump 13 has the maximum height of bump 13 in thenormal direction of semiconductor layer 11. A disposition and the numberof bumps are not particularly limited and are suitably determinedaccording to purposes.

(2) Bump Embedding Process

Next, at least head top part 131 of bump 13 is embedded into firstadhesive layer 22 ((b) of FIG. 1A). With this, damage of bump 13 issuppressed in the thinning process to be subsequently performed. Headtop part 131 of bump 13 is embedded into first adhesive layer 22 byadhering protection tape 20 including first adhesive layer 22 to firstsurface 10X. Protection tape 20 may be pressurized after being adheredto first surface 10X. Particularly, protection tape 20 is adhered tobump 13 while being pressurized and heated in the vacuum to thereby makebump 13 easily embedded into first adhesive layer 22.

Protection Tape

Protection tape 20 includes, for example, base material 21 and firstadhesive layer 22. Base material 21 is a support of first adhesive layer22. As the material of base material 21, for example, polyester such aspolyethylene terephthalate and polyimide are included. The thickness ofbase material 21 is not particularly limited, but preferably 30 to 150μm from the point of view of handleability and functionality as asupport.

First adhesive layer 22 preferably has flexibility enough to followalong at least head top part 131 of bump 13. Additionally, firstadhesive layer 22 preferably has peelability enough to be peeled offfrom first surface 10X without damaging or peeling off bump 13. From apeelability point of view, an adhesive force between bump 13 and firstadhesive layer 22 is preferably smaller than an adhesive force betweenbump 13 and circuit layer 12. First adhesive layer 22 preferably has theheat resistance enough to withstand a temperature condition (forexample, baking conditions (150° C. for approximately 5 minutes) informing a resist mask) in subsequent processes.

Such first adhesive layer 22 is formed by a laminate structure of, forexample, a layer containing acrylic resin (acrylic resin layer) and alayer containing silicone resin (silicone resin layer). In this case, anacrylic resin layer is disposed on a base material 21 side. From theflexibility point of view, a thickness of the acrylic resin layer ispreferably larger than that of the silicone resin layer. Particularly,the thickness of the acrylic resin layer is preferably 5 to 20 times thethickness of the silicone resin layer. First adhesive layer 22 may beformed with, for example, ultraviolet curable resin (for example, amixture of acrylic resin, a photopolymerizable oligomer, and aphotopolymerization initiator). In this case, first adhesive layer 22 isirradiated with ultraviolet ray such that protection tape 20 is easilypeeled off from substrate 10.

Thickness T (see FIG. 3A) of first adhesive layer 22 is not particularlylimited as long as at least head top part 131 of bump 13 is capable ofbeing embedded into first adhesive layer 22. Head top part 131 of bump13, as illustrated in FIG. 2, is a portion occupying a range extendingfrom the top of bump 13 to a point which corresponds to one-third heightHb of bump 13. That is, a thickness of first adhesive layer 22 is notparticularly limited as long as the thickness is greater than or equalto one-third height Hb of bump 13. Particularly, from a bump 13protection point of view, thickness T of first adhesive layer 22 ispreferably greater than height Hb of bump 13. On the other hand, from acost point of view, thickness T of first adhesive layer 22 is preferablyless than or equal to twice height Hb of bump 13. Specifically,thickness T of first adhesive layer 22 is 40 to 400 μm and may be 100 to300 μm. For example, in a case where height Hb of bump 13 is 65 μm,thickness T of first adhesive layer 22 may be 115 μm. In this case, athickness of base material 21 is, for example, 50 μm. Thickness T offirst adhesive layer 22 is an average thickness of first adhesive layer22 in the normal direction of semiconductor layer 11.

As illustrated in FIG. 3A, bump 13 may be embedded into first adhesivelayer 22 in such a way that a surface in head top part 131 and a surfaceof a portion (that is, base 132) other than head top part 131 of bump 13as well as other than contact part 133 of bump 13 which is in contactwith first surface 10X are covered by first adhesive layer 22. Withthis, damage or change in quality of bump 13 is further suppressed inthe thinning process, the mask forming process, and the singulationprocess. In this case, thickness T of first adhesive layer 22 is greaterthan height Hb of bump 13.

On the other hand, the surface of base 132 of bump 13 may not be coveredby first adhesive layer 22. For example, as illustrated in FIG. 3B, bump13 may be embedded into first adhesive layer 22 in such a way that voidS surrounded by base 132, first adhesive layer 22, and first surface 10Xis formed in a region (narrow pitch region R21) between adjacent bumps13 in element region R2. In this case, a contact area between thesurface of bump 13 and first adhesive layer 22 is small and thus, firstadhesive layer 22 is peeled off more smoothly and damage or peeling offof bump 13 is further suppressed in the subsequent bump exposingprocess. However, it is desirable that first adhesive layer 22 and firstsurface 10X are in close contact with each other in dividing region R1.With this, bump 13 is hardly exposed to chemical liquid such as adeveloper or plasma and thus, damage or degradation of bump 13 issuppressed in the thinning process, the mask forming process, and thesingulation process.

(3) Thinning Process

Next, a thinning process ((c) of FIG. 1A) for polishing a portion ofsemiconductor layer 11 to make semiconductor layer 11 thinner isperformed. This is because a thickness of semiconductor layer 11 to beprovided to the singulation process needs to be small from a viewpointof reduction of the processing time or miniaturization of an elementchip or the like in the singulation process, while a certain level ofthickness is required for semiconductor layer 11 in forming circuitlayer 12 on semiconductor layer 11. The thinning process is performed ina state where protection tape 20 is adhered to first surface 10X.

In the thinning process, a surface (second surface 10Y) of a sideopposite to circuit layer 12 of semiconductor layer 11 is ground andsubstrate 10 is made thinner to a desired thickness. During the thinningprocess, bump 13 is protected by protection tape 20. The type ofgrinding apparatus is not particularly limited and includes, forexample, a back grinder provided with a diamond wheel or the like. Afterthe thinning process, a polishing process may be performed on secondsurface 10Y. Before and after the thinning process, a surface of a sideopposite to first surface 10X is referred to as second surface 10Y.

(4) Mask Forming Process

In the present process, mask 30 which covers element region R2 andexposes dividing region R1 is formed in a state where protection tape 20is adhered to first surface 10X ((d) of FIG. 1A). Mask 30 is formed insecond surface 10Y at which bump 13 is not disposed. For that reason,bump 13 is hardly influenced by a developer or the like used information of mask 30. Accordingly, damage or change in quality of bump13 is suppressed in the mask forming process. Additionally, at leasthead top part 131 of bump 13 is embedded into first adhesive layer 22and thus, degradation or damage of bump 13 is further suppressed.Thinned substrate 10 is supported by protection tape 20 and thus, damageor warping of substrate 10 itself is suppressed. Substrate 10 supportedby protection tape 20 is suitably used in a nanoimprint method whichwill be described later.

Mask 30 is formed by removing photosensitive resin corresponding todividing region R1 by the photolithography method, after forming aphotosensitive resin layer on, for example, second surface 10Y, by aspin coating method. The photosensitive resin layer may be adhered tosecond surface 10Y after being formed into a film shape. In replacementof photosensitive resin, mask 30 may be formed by being subjected topatterning by laser scribing after forming a heat-resistant resin layersuch as a polyimide resin layer on second surface 10Y. Furthermore, mask30 can be formed by using the nanoimprint method. The nanoimprint methodis a method in which a mold provided with fine irregularities callednano molds are pushed to photosensitive resin coated on second surface10Y or a photosensitive resin film adhered to second surface 10Y andthen, the mold is irradiated with ultraviolet, and fine irregularitiesare transferred onto the photosensitive resin or the photosensitiveresin film. In the present exemplary embodiment, bump 13 is embeddedinto first adhesive layer 22 and thus, second surface 10Y of substrate10 is substantially flat. For that reason, an adjustment of the depth offocus in exposure in the photolithography method or an adjustment of animprinting pressure in the nanoimprint method becomes easy and formingof mask 30 on second surface 10Y becomes easy.

(5) Holding Process

In the present process, substrate 10 is adhered to holding tape 41 to beheld such that first surface 10X opposes holding tape 41 supported onframe 42 ((e) of FIG. 1A). Substrate 10 is held on holding tape 41 tothereby enhance handleability in the subsequent singulation process andthe bump exposing process. In this case, protection tape 20 is notpeeled off and substrate 10 is adhered to holding tape 41 throughprotection tape 20. For that reason, load on bump 13 according topeeling off of protection tape 20 is reduced and damage or contaminationdue to external factors of circuit layer 12 and bump 13 is reduced. Inthe holding process, protection tape 20 is not peeled off and thus,enhancement of productivity can be expected. In the following, frame 42and holding tape 41 fixed to frame 42 may be collectively referred to astransport carrier 40.

In the singulation process, in a case where substrate 10 is placed onstage 211 such that head top part 131 of bump 13 opposes stage 211, bump13 may be damaged. However, protection tape 20 (back grinding tape) usedfor suppressing damage of bump 13 in the thinning process is not peeledoff and is diverted, as it is, to be used in the subsequent holdingprocess and the singulation process such that damage of bump 13 issuppressed in the singulation process. For that reason, a dicing tapegenerally used for applications can be used in holding tape 41 which isused for holding substrate 10 without the need of a functionality orconfiguration (for example, a thick adhesive layer for covering bump 13)for protecting bump 13. That is, it is possible to realize the presentexemplary embodiment in which plasma is irradiated from second surface10Y to singulate substrate 10 by using the back grinding tape and dicingtape used conventionally. Accordingly, element chip 100 in which damageof bump 13 is suppressed is obtained while suppressing cost increase.

Holding Tape

Holding tape 41 is not particularly limited. Holding tape 41 includes,for example, support 411 and second adhesive layer 412. A material ofsupport 411 is not particularly limited and includes, for example, afilm (resin film) containing thermoplastic resin such as polyolefin suchas polyethylene and polypropylene and polyester such as polyethyleneterephthalate. In the resin film, a rubber component (for example,ethylene-propylene rubber (EPM) and ethylene-propylene-diene rubber(EPDM)) for adding stretchability, a plasticizer, a softner, anantioxidant, various kinds of additives such as a conductive materialmay be blended. The thermoplastic resin may have a functional groupwhich exhibits photopolymerization reaction such as an acrylic group.The thickness of support 411 is not particularly limited and is, forexample, 50 to 300 μm and preferably 50 to 150 μm. Second adhesive layer412 preferably contains an adhesion component (for example, ultravioletcuring type acrylic adhesive agent) of which an adhesive force isreduced by ultraviolet (UV) irradiation. This is because element chip100 is easily peeled off from second adhesive layer 412 and the pickingup becomes easy by performing UV irradiation when element chip 100 ispicked up. The thickness of second adhesive layer 412 is notparticularly limited, but is preferably 5 to 100 μm, more preferably 5to 15 μm from an adhesiveness or cost point of view.

Frame

Frame 42 is a frame includes an opening having an area equal to orlarger than the entirety of substrate 10 illustrated in FIG. 4A, and hasa predetermined width and substantially fixed thin thickness. The frame42 has such a degree of rigidity to be able to transport holding tape 41and substrate 10 in a state where holding tape 41 and substrate 10 areheld. As illustrated in FIG. 4B, second adhesive layer 412 is placed tooppose frame 42 and the outer peripheral edge of second adhesive layer412 is adhered to one surface of frame 42 to thereby fix holding tape 41to frame 42. A shape of the opening of frame 42 is not particularlylimited and may be, for example, a circular shape, a rectangular shape,and a polygon such as a hexagon. Frame 42 may be provided with notch 42a or corner cut 42 b for positioning. The materials of frame 42 include,for example, metal such as aluminum or stainless steel and resin.Substrate 10 is adhered through protection tape 20 in such a way thatfirst surface 10X opposes the portion of second adhesive layer 412exposed from the opening of frame 42.

In the holding process, substrate 10 is preferably held on holding tape41 after being placed on a stand (not illustrated). Substrate 10 isplaced on the stand such that second surface 10Y opposes the stand andsecond adhesive layer 412 is adhered to first surface 10X of substrate10 through protection tape 20. A surface of the stand is preferablycovered by fluororesin (polytetrafluoroethylene, polyvinylidenefluoride, tetrafluoroethylene-ethylene copolymer, or the like). Withthis, even in a case where the surface of the stand comes in contactwith mask 30 formed on second surface 10Y of substrate 10, peeling offof mask 30 is easily suppressed.

The mask forming process and the holding process are performed in anyorder whatever. The holding process may be conducted after the maskforming process and the mask forming process may be conducted after theholding process. In a case where the holding process is conducted afterthe mask forming process, it is possible to use a general resist coatingapparatus or exposing apparatus for substrate-processing in forming themask. On the other hand, in a case where the mask forming process isconducted after the holding process, it is necessary to use a resistcoating apparatus or exposing apparatus which can handle frame 42. Thisis because the mask is formed for the transport carrier which holdssubstrate 10 as a target. However, the latter case is preferable in thatin the holding process, contact of the surface of the stand and mask 30formed on second surface 10Y can be avoided and thus deformation of mask30 can be suppressed. Furthermore, the surface of the stand is hardlycontaminated and thus, a maintenance frequency of the stand is reduced.

(6) Placement Process

After the mask forming process and the holding process, substrate 10 isplaced on stage 211 provided inside the plasma processing apparatusthrough protection tape 20 and holding tape 41.

In the following, description will be specifically made on plasmaprocessing apparatus 200 used in the plasma etching process and theplasma dicing process with reference to FIG. 5, but a plasma processingapparatus is not limited thereto. FIG. 5 schematically illustrates across-section of a structure of plasma processing apparatus 200 used inpresent exemplary embodiment.

Plasma processing apparatus 200 is provided with stage 211. Transportcarrier 40 is placed on stage 211 such that the surface of holding tape41 on which substrate 10 is held faces upward. Cover 224, which includeswindow portion 224W for covering at least a portion of frame 42 andholding tape 41 and exposing at least a portion of substrate 10, isdisposed above stage 211.

Stage 211 and cover 224 are disposed inside vacuum chamber 203. Vacuumchamber 203 has a substantially cylindrical shape of which the upperpart is opened and the upper opening is closed by dielectric member 208which is a lid. As materials for constituting vacuum chamber 203,aluminum, stainless steel (SUS), aluminum of which surface is subjectedto the alumite treatment, and the like may be exemplified. As materialsfor constituting dielectric member 208, dielectric materials such asyttrium oxide (Y₂O₃), aluminum nitride (AlN), alumina (Al₂O₃), quartz(SiO₂) or the like may be exemplified. Antenna 209 as an upper electrodeis disposed above dielectric member 208. Antenna 209 is electricallyconnected with first high frequency power source 210A. Stage 211 isdisposed on the bottom side within vacuum chamber 203.

Gas introduction port 203 a is connected to vacuum chamber 203. Processgas source 212 which is a supply source of process gas and ashing gassource 213 are respectively connected to gas introduction port 203 a bypipes. Vacuum chamber 203 is provided with exhaust port 203 b andpressure reducing mechanism 214, which includes a vacuum pump exhaustinggas within vacuum chamber 203, is connected to exhaust port 203 b.

Stage 211 is provided with electrode layer 215, metal layer 216, base217 supporting electrode layer 215 and metal layer 216, and outerperiphery 218 surrounding electrode layer 215, metal layer 216, and base217, each of which has a circular shape. Outer periphery 218 isconstituted with metals having conductivity and etching resistance andprotects electrode layer 215, metal layer 216, and base 217 from plasma.On the upper surface of outer periphery 218, annular ring shaped outerperipheral ring 229 is disposed. Outer peripheral ring 229 is forprotecting the upper surface of outer periphery 218 from plasma.Electrode layer 215 and outer peripheral ring 229 are constituted with,for example, dielectric materials described above.

An electrode portion (in the following, referred to as ESC electrode219) constituting an electrostatic attraction mechanism and highfrequency electrode portion 220 electrically connected to second highfrequency power source 210B are disposed inside electrode layer 215. DCpower source 226 is electrically connected to ESC electrode 219. Theelectrostatic attraction mechanism is constituted with ESC electrode 219and DC power source 226.

Metal layer 216 is constituted with, for example, aluminum of whichsurface is subjected to alumite coating. Coolant flow path 227 is formedinside metal layer 216. Coolant flow path 227 cools down stage 211.Stage 211 is cooled down and accordingly, holding tape 41 placed onstage 211 is cooled down and cover 224 of which a portion is in contactwith stage 211 is also cooled down. With this, substrate 10, protectiontape 20 and holding tape 41 are suppressed from being damaged whensubstrate 10, protection tape 20 and holding tape 41 are heated duringplasma processing. Coolant within coolant flow path 227 is circulated bycoolant circulator 225.

A plurality of supporting portions 222 which penetrate through stage 211are disposed in the vicinity of outer periphery of stage 211. Supportingportions 222 are driven to be moved up and down by elevation mechanism223A. When transport carrier 40 is transported into vacuum chamber 203,transport carrier 40 is handed over to supporting portions 222 raised toa predetermined position. Supporting portions 222 support frame 42 oftransport carrier 40. An upper end surface of supporting portions 222 islowered to a level which is equal to or less than the level of stage 211such that transport carrier 40 is placed on a predetermined position onstage 211.

A plurality of elevation rods 221 are connected to an end portion ofcover 224 and cover 224 is able to be moved up and down. Elevation rods221 are driven to be moved up and down by elevation mechanism 223B.Moving up and down operations of cover 224 by elevation mechanism 223Bcan be performed independently from elevation mechanism 223A.

Controller 228 controls operations of elements constituting plasmaprocessing apparatus 200 which includes first high frequency powersource 210A, second high frequency power source 210B, process gas source212, ashing gas source 213, pressure reducing mechanism 214, coolantcirculator 225, elevation mechanism 223A, elevation mechanism 223B, andan electrostatic attraction mechanism.

In the placement process, first, substrate 10 held in transport carrier40 is carried into vacuum chamber 203. Cover 224 is moved up to apredetermined position within vacuum chamber 203 by driving elevationrod 221. A gate valve (not illustrated) is open and transport carrier 40is carried into vacuum chamber 203. A plurality of supporting portions222 are on standby in a state of being moved up. When transport carrier40 reaches a predetermined position above stage 211, transport carrier40 is handed over to supporting portions 222. Transport carrier 40 ishanded over to the top surface of supporting portions 222 in such a waythat second adhesive layer 412 of holding tape 41 faces upward.

When transport carrier 40 is handed over to supporting portions 222, thegate valve is closed and vacuum chamber 203 is placed in a sealed state.Next, supporting portions 222 is started to move down. The top surfaceof supporting portions 222 is moved down to a level which is equal to orless than the level of stage 211 such that transport carrier 40 isplaced on stage 211. Subsequently, elevation rod 221 is driven.Elevation rod 221 moves cover 224 down to a predetermined position. Inthis case, a distance between cover 224 and stage 211 is adjusted so asto make it possible for cover 224 to cover frame 42 without coming intocontact with transport carrier 40. With this, frame 42 and a portion ofholding tape 41 at which substrate 10 is not held are covered by cover224 without coming into contact with each other and substrate 10 isexposed from window portion 224W of cover 224.

Cover 224 is doughnut-shaped having, for example, a substantiallycircular external contour and has a fixed width and a thin thickness. Aninner diameter (diameter of window portion 224W) of cover 224 is smallerthan that of frame 42 and an outer diameter of cover 224 is larger thanthat of frame 42. Accordingly, when transport carrier 40 is placed at apredetermined position of stage 211 and cover 224 is moved down, cover224 can cover at least a portion of holding tape 41 and frame 42. Atleast a portion of substrate 10 is exposed from window portion 224W. Inthis case, cover 224 does not contact with any of frame 42, holding tape41, and substrate 10. Cover 224 is constituted with, for example, adielectric material such as ceramics (for example, alumina and aluminumnitride) or quarts, or metal such as aluminum or aluminum of whichsurface is subjected to the alumite treatment.

After transport carrier 40 is handed over to supporting portions 222, avoltage is applied from DC power source 226 to ESC electrode 219. Withthis, holding tape 41 comes in contact with stage 211 and iselectrostatically sucked onto stage 211 at the same time. Application ofthe voltage to ESC electrode 219 may be started after holding tape 41 isplaced on stage 211 (after being come into contact therewith).

(7) Singulation Process

After the placement process, the dividing regions R1 of substrate 10 areplasma etched to a depth which extends from second surface 10Y to firstsurface 10X in a state where substrate 10 is placed on stage 211 to forma plurality of element chips 100 from substrate 10 ((g) of FIG. 1A).

In this case, substrate 10 is placed on stage 211 in such a way thatsecond surface 10Y on which bumps 13 are not disposed faces antenna 209which is a plasma source. That is, plasma etching is performed in astate where bump 13 is suppressed from being irradiated with plasma. Atleast head top part 131 of bump 13 is embedded into first adhesive layer22 to be protected. For that reason, effects described may be obtained.Additionally, semiconductor layer 11 is made thin and thus, plasmairradiation time onto substrate 10 is reduced in the singulation processand degradation and damage of bump 13 due to plasma is furthersuppressed.

A plasma generation condition is set according to materials of a layerto be etched (semiconductor layer 11 and circuit layer 12) or the like.In the present process, semiconductor layer 11 and circuit layer 12 ofwhich materials are different from each other are etched and thus, it ispreferable that plasma etching is performed by switching to thecondition according to each layer. For example, after semiconductorlayer 11 is removed by a Bosch process which will be described later,circuit layer 12 may be removed by plasma in which process gascontaining Ar is used as raw material.

In the Bosch process, semiconductor layer 11 is vertically etched in adepth direction. In a case where semiconductor layer 11 contains Si, aprotective film deposition step, a protective film etching step, and Sietching step are sequentially repeated to excavate semiconductor layer11 in the depth direction, in the Bosch process.

The protective film deposition step is performed, for example, under theprocessing condition that a pressure inside vacuum chamber 203 isadjusted to 15 to 25 Pa, electric power of 1500 to 2500 W is input toantenna 209 from first high frequency power source 210A, and electricpower of 0 to 50 W is input to high frequency electrode portion 220 fromsecond high frequency power source 210B, for 2 to 15 seconds, whilesupplying C₄F₈ of 150 to 250 sccm as raw material gas. Here, sccm is aunit of gas flow rate. 1 sccm is a flow rate indicating that gas at 0°C. and 1 atmosphere of pressure (under the standard state) flows by 1cm³ for 1 minute.

The protective film etching step is performed, for example, under theprocessing condition that a pressure inside vacuum chamber 203 isadjusted to 5 to 15 Pa, electric power of 1500 to 2500 W is input toantenna 209 from first high frequency power source 210A, and electricpower of 300 to 1000 W is input to high frequency electrode portion 220from second high frequency power source 210B, for 2 to 10 seconds, whilesupplying SF₆ of 200 to 400 sccm as raw material gas.

The Si etching step is performed, for example, under the processingcondition that a pressure inside vacuum chamber 203 is adjusted to 5 to15 Pa, electric power of 1500 to 2500 W is input to antenna 209 fromfirst high frequency power source 210A, and electric power of 50 to 500W is input to high frequency electrode portion 220 from second highfrequency power source 210B, for 10 to 20 seconds, while supplying SF₆of 200 to 400 sccm as raw material gas.

Under the conditions described above, the protective film depositionstep, the protective film etching step, and the Si etching step arerepeated to thereby make it possible to vertically etch semiconductorlayer 11 containing Si in the depth direction at a rate of 10 μm/min.

In a case where circuit layer 12 contains a metal, the plasma etching isperformed, for example, under the condition that a pressure insidevacuum chamber 203 is adjusted to 0.2 to 1.5 Pa, high frequency electricpower of 1500 to 2500 W having a frequency of 13.56 MHz is input toantenna 209 from first high frequency power source 210A, and highfrequency electric power of 500 to 1800 W having a frequency of 100 kHzor more (for example, 400 to 500 kHz or 13.56 MHz) is input to highfrequency electrode portion 220 from second high frequency power source210B, while supplying mixed gas of CF₄ and Ar (CF₄:Ar=1:4) of 150 to 250sccm as raw material gas.

After substrate 10 is singulated, ashing is performed. First, processgas (for example, oxygen gas and mixed gas containing oxygen gas and gascontaining fluorine) for ashing is introduced into vacuum chamber 203from ashing gas source 213. On the other hand, vacuum chamber 203 isexhausted by pressure reducing mechanism 214 to maintain a pressureinside vacuum chamber 203 to a predetermined pressure. Oxygen plasma isgenerated within vacuum chamber 203 due to input of the high frequencypower from first high frequency power source 210A and mask 30 on thesurface of substrate 10 (element chip 100), which is exposed from windowportion 224W of cover 224 and singulated, is removed.

Ashing is performed, for example, under the condition that a pressureinside vacuum chamber 203 is adjusted to 5 to 30 Pa, electric power of1500 to 2500 W is input to antenna 209 from first high frequency powersource 210A, and electric power of 0 to 300 W is input to high frequencyelectrode portion 220 from second high frequency power source 210B,while supplying mixed gas of CF₄ and O₂ (CF₄: O₂=1:100) of 200 to 500sccm as raw material gas.

When ashing is ended, gas inside vacuum chamber 203 is exhausted and thegate valve is open. Transport carrier 40 holding a plurality of elementchips 100 is carried out from plasma processing apparatus 200 by atransport mechanism which enters from the gate valve. When transportcarrier 40 is carried out, the gate valve is closed quickly. A carryingout process of transport carrier 40 may be performed in a reverseprocedure to the procedure for placing substrate 10 described above onstage 211. That is, after cover 224 is moved up to a predeterminedposition, suction of transport carrier 40 onto stage 211 is released bymaking an application voltage to ESC electrode 219 zero and supportingportions 222 are moved up. After supporting portions 222 are moved up toa predetermined position, transport carrier 40 is carried out.

(8) Bump Exposing Process

After the singulation process, first adhesive layer 22 is peeled off andbump 13 is exposed again. The bump exposing process may be a portion ofa pickup process of element chip 100 ((h) of FIG. 1A).

Pickup of element chip 100 is performed by pushing singulated elementchip 100 together with protection tape 20 up from a holding tape 41 sideby push-up pin 60. With this, first adhesive layer 22 is peeled off fromfirst surface 10X. Accordingly, at least a portion of element chip 100is also raised and bump 13 is exposed and thus, the pickup of elementchip 100 becomes possible. In this case, bump 13 is covered byprotection tape 20 and holding tape 41 and thus, damage by push-up pin60 is avoided. As described above, according to the present exemplaryembodiment, etching residue is hardly generated in the dividing regionsduring the plasma dicing process. Accordingly, recognition accuracy andpickup performance are enhanced in the pickup process and thus, yield inproduction is also enhanced.

As illustrated in FIG. 1C, the pickup of element chip 100 may beperformed after protection tape 20 and holding tape 41 are peeled offfrom first surface 10X and pickup tape 52 is adhered to second surface10Y. In this case, circuit layer 12 and bump 13 face the upper surfaceand thus, accuracy of recognizing element chip 100 is enhanced andpickup failure is reduced.

Pickup tape 52 is preferably fixed to pickup frame 51 from ahandleability point of view, similar to holding tape 41. Pickup frame 51may have the material and shape similar to those of frame 42. Thematerial of pickup tape 52 may be the same as that of holding tape 41.On the other hand, holding tape 41 and pickup tape 52 may be formed withmaterials according to respective purposes. For example, flexibilitysuitable for pickup is required for holding tape 41 and a film includingresin with high crystallinity can be used for holding tape 41. Such aresin film is excellent in heat resistance and plasma resistance. Thatis, holding tape 41 excellent in plasma resistance can be used in thesingulation process. For that reason, it is possible to perform, forexample, the plasma dicing while inputting a high-frequency power of 100kHz or more (for example, 400 to 500 kHz, or 13.56 MHz) to highfrequency electrode portion 220 and applying a high bias voltage. Withthis, high speed processing is possible and productivity is enhanced.

Element chip 100 capable of being obtained by a manufacturing method ofthe present exemplary embodiment is excellent in smoothness of a sidesurface thereof. This is because, as described above, during the plasmadicing, metals constituting bump 13 are suppressed from beingredeposited to substrate 10. Such element chip 100 is excellent inflexural strength and molding failure is hard to occur in packaging. Theelectrical characteristics of element chip 100 are hardly degenerated.This is because in the plasma dicing, bump 13 is prevented from beingetched and the metals described above are suppressed from beingredeposited to substrate 10.

Even in a case where bump 13 contains copper and process gas containingsulfur hexafluoride (SF₆) is used in the plasma dicing, element chip 100capable of being obtained is excellent in reliability. This is becausecopper contained in bump 13 is hardly sulfurized. Similarly, even in acase where process gas used in the plasma dicing or ashing gas containsfluorine or oxygen, fluorination or oxidation of the surface of bump 13is hard to occur. Even in a case where process gas used in the plasmadicing contains fluorocarbon such as C₄F₈, a reaction product containingcarbon is hardly deposited to the surface of bump 13. For that reason,it is possible to obtain element chip 100 in which an increase incontact resistance or a decrease in connection strength of bump 13 issuppressed and which has high reliability can be obtained.

Second Exemplary Embodiment

The present exemplary embodiment is similar to the first exemplaryembodiment except that the mask forming process is performed in a statewhere protection tape 20 is adhered to the first surface and protectiontape 20 is peeled off from the first surface before the holding process.In FIG. 6, a manufacturing method of an element chip of the presentexemplary embodiment is illustrated ((a) to (h)). (a) to (d) and (h) ofFIG. 6 respectively correspond to (a) to (d) of FIG. 1A and FIG. 1C.

In the present exemplary embodiment, after the mask forming process ((d)of FIG. 6), protection tape 20 is peeled off from first surface 10X andholding tape 41 supported on frame 42 is adhered to first surface 10X soas to embed at least head top part 131 of bump 13 into second adhesivelayer 412 of holding tape 41 ((e) of FIG. 6). That is, the bumpembedding process and the holding process are conducted at the sametime. With this, the processes are simplified and productivity isenhanced. In this case, second adhesive layer 412 has a thickness enoughto embed at least head top part 131 of bump 13. Second adhesive layer412 preferably has the same configuration as first adhesive layer 22described above. Protection tape 20 may be peeled off before the maskforming process.

In the placement process, substrate 10 is placed on stage 211 throughholding tape 41 ((f) of FIG. 6). For that reason, substrate 10 is easilycooled down compared to the first exemplary embodiment in whichsubstrate 10 is placed on stage 211 through holding tape 41 andprotection tape 20. Also, in the present exemplary embodiment, plasma isirradiated from second surface 10Y ((g) of FIG. 6) and thus, degradationand damage of bump 13 are suppressed.

The pickup process (bump exposing process) may be performed bytransferring substrate 10 onto pickup tape 52 ((h) of FIG. 6) or may beperformed in a state where element chip 100 is held in holding tape 41.In the former case, a layer on which element chip 100 is held becomesthinner compared to the first exemplary embodiment and thus, elementchip 100 is easily pushed upward.

In the exemplary embodiment according to the present disclosure,degeneration and damage of the bump is suppressed and thus, theexemplary embodiment may be useful as a method for singulating thesubstrate provided with the bumps to manufacture the element chip.

What is claimed is:
 1. An element chip manufacturing method comprising:a preparation process of preparing a substrate which includes a firstsurface including an exposed bump and a second surface opposite to thefirst surface and includes a plurality of element regions defined bydividing regions; a bump embedding process of adhering a protection tapehaving an adhesive layer to the first surface and embedding at least ahead top part of the bump into the adhesive layer; a thinning process ofgrinding the second surface in a state where the protection tape isadhered to the first surface and thinning the substrate, after the bumpembedding process; a mask forming process of forming a mask which coversthe element regions in the second surface and exposes the dividingregions, after the thinning process; a holding process of arranging thefirst surface to oppose a holding tape supported on a frame and holdingthe substrate on the holding tape; a placement process of placing thesubstrate on a stage provided inside of a plasma processing apparatusthrough the holding tape, after the mask forming process and the holdingprocess; and a singulation process of plasma etching the dividingregions to a depth which extends from the second surface to the firstsurface and forming a plurality of element chips from the substrate,after the placement process.
 2. The element chip manufacturing method ofclaim 1, wherein the mask forming process is performed in a state wherethe protection tape is adhered to the first surface.
 3. The element chipmanufacturing method of claim 1, wherein a thickness of the adhesivelayer is greater than a height of the bump.
 4. The element chipmanufacturing method of claim 3, wherein, in the bump embedding process,a surface of the head top part of the bump and a surface of the bumpother than the head top part come in contact with the adhesive layer. 5.The element chip manufacturing method of claim 1, wherein, a void isformed in the bump embedding process, the void being surrounded by (i) asurface of the bump that is other than the head top part and that isother than a portion at which the bump is in contact with the firstsurface, (ii) the adhesive layer, and (iii) the first surface.
 6. Theelement chip manufacturing method of claim 1, wherein, in the holdingprocess, the substrate is held on the holding tape in such a way thatthe first surface faces the holding tape through the protection tape. 7.The element chip manufacturing method of claim 1, further comprising,before the holding process and after the thinning process: a bumpexposing process of peeling off the protection tape from the firstsurface and exposing the bump.
 8. The element chip manufacturing methodof claim 1, wherein the substrate includes a semiconductor layer and acircuit layer laminated on a first surface side of the semiconductorlayer and including the bump, and in the preparation process, thesubstrate in which the semiconductor layer is exposed in the dividingregions is prepared.